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Tag: colour

First steps exploring maiolica in more depth, with multiple recipes, temperatures and tests.

I want to extend my knowledge of colourful earthenware glazes and in-glaze, building on experience from last year.
I specifically looked in majolica/tin glaze books in library and had a productive meeting with Matt to discuss some issues and technicalities.

Maiolica, or Faience is very common in ceramic traditions of Slovakia, and mostly depicting nature and colourful vegetation. It’s aspiration, but still common and down to earth.
That’s why I feel it is quite fitting for the finish of my ceramic growths, through colourful spills or patterns.

I identified 6 different white majolica recipes of various temperatures, materials and finishes. I need to test the fit and compatibility of each glazes with the bodies I use, quality, and colour response.
I had good advice such as higher bisque (1050-1060C), heating up pieces before applying the glaze, adding up to 2% Rutile to increase colour warmth, mixing 1 part stain material to 6 parts transparent glaze and adding 2-3 part water to loosen the mixture if necessary.

I had rather hard first few firings due to kiln malfunction, or hectic timetable and not firing the test kiln properly. So many more tests needed.

Returning to Subject Module, I started to explore colour in glazes on my own, to help me develop specific colour pallet for my Subject work.

Orange being the most prevalent colour in Penguin Books designs, it provides a great depth of symbolism and context associated with the cultural impact Penguin Books had in UK and other English speaking countries. It brought inexpensive fiction and non-fiction to the mass market, educating, and having impact on public debate in Britain, through its books on British culture, politics, the arts, and science.
Therefore, I’m using orange as colour of possibility for social and personal growth.
I found number of good colour pallets around orange, but one with split complementary colours: blue and purple stood out visually, and belonging in the Penguin colour scheme with dark blue representing Biography and Purple representing Essays.

I started with a search for multiple recipes of the chosen colours in EW and SW, which would give me glaze bases and colours which I could then combine and refine.

I tested 4 SW recipes with one very successful Barium based glaze producing interesting dark blues with orangey halo on White Saint Tomas, and another glossy Soto Amber with interesting double colouration, but in green and browns.

Adapting the 2 base glazes, I stained them with commercial stains, which however burned out or in case of Lilac and Rosso Red Stains just reduced in vibrancy.

Therefore, I started experimenting with combinations of oxides to mixed into my leftover stained batches, referencing oxide combination sheet in our glaze room.

In the Barium based glaze I used:
Vanadium + Cobalt Carbonate + Titanium Dioxide produced matter, more even, lighter blue.
Manganese Carbonate produced very dark uneven purple.
Vanadium + Rutile didn’t show up and the glaze remained white.

I had more luck in the EW glazes due to the simplicity of using commercial stains.

Finding another 4 different glazes, mainly Lead based, but one with Wollastonite and Strontium carbonate as fluxes which proved as most stable on different clays, pleasant surface and gloss, not settling down and good colour response.

I was able to use colorant combinations from the other glazes to adapt the non-toxic base glaze, and experiment with other combinations, to produce a range of oranges, yellows and dark blue purples.

If I had more time I would really go for a bit more scientific/controlled way of testing the additions to perfect the colours, rather than my very quick, mostly intuitive decision making.

The fact that I opted for spraying my final work, made the glaze much brighter, but at least I’m not having brush streaks or loosing any details in texture.

The latest test piece glazed with my Penguin Purple, Penguin Yellow, Penguin White and Penguin Orange applied by spraying were acceptable. The one directional application even suggested sun exposure, as if sun rays sprayed the piece, giving direction to the growth.

Starting with Slip technical, exploring colours in slips with Morgan alongside Field module.

I started with a search across library books and the internet for base, white slip recipes of which we mixed 7.

We applied them on terracotta and White Saint Thomas tiles in 3 various layers fired to EW and SW temperatures, half glazed. Also fired on its own.
The blobs of slip were created by piping about 20ml of the individual slips onto plaster bat and gently smearing them. However, they proved extremely fragile after drying, some of them quickly cracking in the process of drying. Anyway, the colour was the same as 3 coats on the tiles; on the other hand, we wanted the blobs of slips for more interesting and easier presentation of our outcomes, giving us possibility to use them to create an installation piece.

The experiment allowed us to see that the simple recipe used in our glaze room: 50/50 of Ball and China clay has the best result in producing white slip in EW temperature, meanwhile using Porcelain powder slip is whitest for SW temperature.

Morgan’s temperature test showed us the colour changes in number of oxides and staines in EW and SW temperature.
Using the chosen 50/50 slip he stained it with Red, Yellow, Purple and Synthetic Iron Oxides, as well as Coral stain and Chrome Oxide.
Half glazed, they reveal a dramatic change in colour.
This test made us stick with EW temperatures, with added bonus of reducing cost and environmental impacts, but being aware of increased fragility of EW products.

To further see the colour response of each slip recipe, we added 10% of Yellow stain to each recipe, bisque fired and half glazed at EW temperature, on terracotta tiles.
Most of them look the same, except 1 weird recipe that melts on SW.

These experiments gave us really just the starting point, establishing processes and testing techniques, as well as backing up choice for base slip and temperature.
Rigorous testing of combinations of stains and oxides.

We want to be able to produce a specific colour pallet in specific shades, similar to Jin Eui Kim’s carefully mixed tonal range of his engobes, to create an illusion of curves and voids.

Slip

Looking at my object from the Ken Stradling Collection, I wanted to try and recreate the plywood that created the curves and form of the Penguin Donkey in clay.
Using slips seemed like the easiest option to start with, applying it onto a plaster bat with a brush, layer upon layer of blue and white as well as black and white, drying them slightly with a heat gun to prevent the colours mixing.
The problem arise when taking the ply-clay slabs from the bat. I tried to use thin metal kidney, but the slip continued to tear and distort even when drier.

I assume the difficulty of removing slabs from plaster are due to the thinnes of the pieces. Anyway, I wanted the overall thickness, as well as the thickness of individual layers to be much thicker, closer to the thickness of real plywood.

I mixed a bigger quantities of slip to experiment with, with different colours to try various colour combinations.
I chose a specific colour palette based on the most widespread Penguin Books colour – Orange, and its split complementary colours to work nicely together, layered upon each other.
In Penguin Books’ categorising, Orange is representing fiction, whereas Blue is for bibliographies and Purple for essays.
Further colours close to the 3 split complementary that I will consider to use is Yellow (miscellaneous), Cerise (travel and adventure) and Pink (drama).

I made multiple thin guides in the wood workshop to guide me at making the individual layers uniformed. The scraping problem didn’t reoccur again, and the thickness and uniformity was ideal.
However, I did use quite a lot of slip; but more importantly, I wasn’t able to bend the slabs easily at all.
I was only able to create a small curved pieces, with quite a lot of cracks.

I think for next trial I’ll have to investigate adding a paper pulp to the slip to make it more flexible when forming, as well as create a plaster moulds to bend the slabs over into desirable form.

I also tried to paint the slip over a pieces of paper to help remove the slip slabs from plaster and make the forming easier. I attempted to recreate and enlarge some of previous tests, but it didn’t work that well, having difficulty to join the sides and hold the shape.

Glazes

A series of 10 melt test of simple combination at EW temperature (1050-1070C).
I started with China Clay and Flint with additions of Borax, High Alkali or Calcium Frit, or Potash Feldspar, Wollastonite or Strontium Carbonate, with additions of orange stain or Rutile for colour.

I played with their values on http://www.glazesimulator.com/ to predict how they could behave.

Few of them didn’t fuse, but most of them turned into a glaze with different matt, porridge like or shiny transparent effects.